Silently departing from the bill of quantities is not correcting — it's deviating
A tenderer who uses a different quantity than prescribed in the bill of quantities for a lump-sum post without explicitly flagging it commits a substantial irregularity, not a correctable arithmetic error.
What happened?
For the renovation of an office floor at VAC Hasselt, the specifications prescribed a lump-sum quantity of 4,770 meters for horizontal cabling (post 64.1.2.3). The tenderer calculated its price based on 3,760 meters (40m × 94 data points) — its own estimate, which only surfaced during the price justification procedure. The contracting authority declared the tender substantially irregular. The tenderer argued it was a material or arithmetic error that should have been corrected ex officio, or that the authority should at least have requested clarification.
Why does this matter?
This judgment draws a sharp line between a correctable arithmetic error and a deliberate choice. Using a different quantity for a lump-sum post means departing from the tender documents — not merely getting a number wrong. The correction mechanisms of articles 34 and 79 §2 of the 2017 Royal Decree are not designed to regularize such deviations. The fact that the recalculated tender would still have been the cheapest is irrelevant: the irregularity concerns the conformity of the offer, not the price outcome.
The lesson
Lump-sum quantities in the bill of quantities are not suggestions. Any deviation must be made explicitly through a formal correction with a justification note (art. 79 §2 Royal Decree 2017). Without that formality, there is no error to correct — there is a non-conforming tender.
Ask yourself
Do we use the exact quantity from the bill of quantities for every lump-sum post, or do we calculate with our own estimates? If we believe a quantity is incorrect: have we included an explicit correction with a justification note in our tender? Do we understand that a price justification procedure is not a second chance to substantively adjust the tender?
About this database
The Council of State (Raad van State / Conseil d'État) is Belgium's supreme administrative court. In disputes over public procurement — from contract awards to tenderer exclusions — the Council of State is the final arbiter. The rulings in this database are summarised by TenderWolf in plain language, with practical lessons for tenderers and contracting authorities. View all rulings →